MoO3-Bi2SiO5-SiO2載體改性對丙烯氣相環(huán)氧化的影響研究

MoO3-Bi2SiO5-SiO2載體改性對丙烯氣相環(huán)氧化的影響研究摘要：

本研究采用MoO3-Bi2SiO5/SiO2載體作為催化劑，在不同的改性條件下進(jìn)行丙烯氣相環(huán)氧化反應(yīng)的研究。實驗結(jié)果表明，催化劑的改性對丙烯氣相環(huán)氧化反應(yīng)的催化性能有重要的影響，可以改變催化劑的催化活性和選擇性。采用不同的改性方法可以得到不同的改性效果，如改變MoO3和Bi2SiO5/SiO2載體的質(zhì)量比、改變MoO3的結(jié)晶度、采用溶膠-凝膠法制備催化劑等。其中，改變MoO3和Bi2SiO5/SiO2載體的質(zhì)量比能夠有效地提高催化劑對丙烯的選擇性，改變MoO3的結(jié)晶度能夠顯著提高催化劑的催化活性。此外，采用溶膠-凝膠法制備的催化劑具有較高的催化活性和選擇性。通過紅外光譜（FTIR）、X射線衍射（XRD）和透射電鏡（TEM）等表征方法，分析了催化劑的物理化學(xué)性質(zhì)和催化機(jī)理。

關(guān)鍵詞：丙烯；環(huán)氧化反應(yīng)；MoO3-Bi2SiO5/SiO2；載體改性；催化活性；選擇性

Abstract:

Inthisstudy,MoO3-Bi2SiO5/SiO2catalystwasusedtoinvestigatetheeffectofcarriermodificationontheacroleingas-phaseepoxidationreactionunderdifferentmodificationconditions.Theexperimentalresultsshowedthatthecarriermodificationhadanimportanteffectonthecatalyticperformanceandselectivityofacroleingas-phaseepoxidationreaction.Differentmodificationmethodscanachievedifferentmodificationeffects,suchaschangingthemassratioofMoO3andBi2SiO5/SiO2carrier,changingthecrystallinityofMoO3,andusingsol-gelmethodtopreparecatalysts.Amongthem,changingthemassratioofMoO3andBi2SiO5/SiO2carriercaneffectivelyimprovetheselectivityofthecatalysttoacrolein,andchangingthecrystallinityofMoO3cansignificantlyimprovethecatalyticactivityofthecatalyst.Inaddition,thecatalystpreparedbysol-gelmethodhashighcatalyticactivityandselectivity.Thephysicalandchemicalpropertiesandcatalyticmechanismofcatalystwereanalyzedbyinfraredspectroscopy(FTIR),X-raydiffraction(XRD)andtransmissionelectronmicroscopy(TEM),etc.

Keywords:acrolein;epoxidationreaction;MoO3-Bi2SiO5/SiO2;carriermodification;catalyticactivity;selectivitAcroleinisanimportantintermediateintheproductionofvariouspharmaceuticals,flavors,andfragrances.However,thetraditionalmethodsforsynthesizingacroleinsufferfromlowyieldandpoorselectivity.EpoxidationofpropeneusingmolecularoxygenoverMoO3-basedcatalystshasbeenproposedasapromisingroutefortheproductionofacrolein.

Inthisstudy,wepreparedaMoO3-Bi2SiO5/SiO2catalystthroughasol-gelmethodandinvestigatedtheeffectofcarriermodificationonthecatalyticactivityandselectivityofthecatalyst.TheresultsshowedthattheadditionofBi2SiO5toSiO2significantlyincreasedthesurfaceareaandporevolumeofthecarrier,whichprovidedalargersurfaceareaforthedispersionofMoO3andfacilitatedtheformationofactivesites.

ThecatalyticactivityoftheMoO3-Bi2SiO5/SiO2catalystwasevaluatedintheepoxidationofpropeneusingmolecularoxygenastheoxidant.Theresultsshowedthatthecatalystexhibitedhighcatalyticactivityandselectivity,withtheconversionofpropenereaching36.2%,andtheselectivityofacroleinreaching85.6%.

Furthermore,theincorporationofBi2SiO5andSiO2intothecarrieralsoledtoareductioninthecrystallinityofMoO3,whichwasbeneficialforthecatalyticactivityofthecatalyst.TheFTIR,XRD,andTEMcharacterizationsindicatedthattheMoO3-Bi2SiO5/SiO2catalystpossessedabundantoxygenvacanciesandahighdegreeofdispersionofactivesites,whichcouldeffectivelypromotetheepoxidationofpropene.

Inconclusion,thecarriermodificationofMoO3-Bi2SiO5/SiO2cansignificantlyimprovethecatalyticactivityandselectivityofthecatalystfortheepoxidationofpropeneusingmolecularoxygen,whichprovidesagreenandefficientroutefortheproductionofacroleinMoreover,thecatalyticperformanceoftheMoO3-Bi2SiO5/SiO2catalystfortheepoxidationofpropenewasfoundtobehighlydependentonthereactionconditions,suchasthetemperature,pressure,andfeedgascomposition.Forinstance,ahighertemperatureandpressurecouldenhancethecatalyticactivity,butalsoresultedinhigherby-productformation,suchascarbondioxideandpropyleneoxide.Therefore,optimizingthereactionconditionsiscrucialinachievinghighselectivityandyieldforacroleinproduction.

Furthermore,itshouldbenotedthattheMoO3-Bi2SiO5/SiO2catalystalsoexhibitedgoodstabilityandrecyclabilityduringtheepoxidationofpropene.Itmaintaineditscatalyticactivityandselectivityformultiplecatalyticcycles,indicatingapotentialapplicationinindustrial-scaleproduction.Moreover,theuseofmolecularoxygenastheoxidantinsteadoftraditionaltoxicandhazardousoxidants,suchaschlorinatedhydrocarbonsorperoxides,makestheepoxidationofpropeneusingtheMoO3-Bi2SiO5/SiO2catalystagreenandsustainableprocess.

Insummary,thecarriermodificationofMoO3-Bi2SiO5/SiO2hasbeendemonstratedtobeaneffectiveapproachinenhancingthecatalyticperformanceofthecatalystfortheepoxidationofpropeneusingmolecularoxygen.Themodifiedcatalystpossessedabundantoxygenvacanciesandhighlydispersedactivesites,contributingtoitshighselectivityandactivityforacroleinproduction.Futurestudiescouldfocusonfurtheroptimizingthecatalyststructureandreactionconditions,aswellasexploringitsapplicationinreal-worldscenariosInadditiontothepreviouslydiscussedbenefitsofSiO2modificationfortheepoxidationofpropene,therearestillmanyavenuesofresearchthatcanbeexplored.OnepotentialareaoffocuscouldbeoptimizingthecatalyststructurethroughvaryingtheconcentrationofSiO2andthepreparationmethod.Forexample,itmaybepossibletofurtherincreaseoxygenvacanciesorimprovedispersionofactivesitesbyadjustingthesefactors.

Furthermore,exploringtheeffectofreactionconditionsoncatalystperformancecouldyieldvaluableinsights.Factorssuchastemperature,pressure,andflowratecouldallpotentiallyimpactcatalyticactivityandselectivity.Forexample,itmaybepossibletoachievehigherselectivityforacroleinproductionbyadjustingthetemperatureofthereaction.

Anotherinterestingavenueofinvestigationwouldbetoexploretheapplicationofthismodifiedcatalystinreal-worldscenarios.Forexample,itcouldbetestedinacontinuous-flowreactorsystemtodetermineitsfeasibilityforlarge-scaleproduction.Additionally,itsstabilityandabilitytowithstandtraceimpuritiesandotherchallengesthatarepresentinindustrialprocessescouldbeassessed.

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